Many fiberglass compositions are currently under development that have improved biosolubility over asbestos fibers and other strongly stable inorganic compositions. The difficulty with many of the compositions that are prepared is that the manufacturing of such fibers may be difficult to control. In addition, the quality product characteristics needed for glass fibers such as the ability to withstand high temperature and moisture environments, yet at the same time to have a desirable biosolubility, may be lacking.
U.S. Pat. No. 4,036,654 to Yale et al. describes glass fiber compositions with a high alkali resistance comprising silica, zirconia from 6 to 20%, as well as high calcia content of from 20 to 45%.
Canadian patent application No. 2,022,446 is directed to a composition of glass fibers which can dissolve in a physiological environment. Preferred components of the composition are silicon dioxide, aluminum oxide, calcium oxide, magnesium oxide, sodium oxide, boron oxide and P.sub.2 O.sub.5. Good performance characteristics are not expected of these fiberglass compositions.
Canadian application No. 2,017,344 has as preferred compositions silicon dioxide, boron oxide, and sodium oxide. The performance characteristics of such glass fibers is sacrificed for high physiological solubility.
International Publication Application No. PCT/US89/02288, published Dec. 14, 1989 as Publication No. WO89/12032, describes inorganic fibers having a silicon extraction rate greater than 0.02 weight percent silicon per day in physiological saline solution. The publication discloses glass fibers comprising silica, magnesia, calcium oxide, alumina and other oxides which have low durabilities in physiological saline solutions.
It is an object of the present invention to describe a glass fiber composition that has high physiological biosolubility.
It is also an object of the present invention to have high biosoluble glass fibers which have high strength and moisture resistance for use in filtration and insulation product applications.
It is a further object of the present invention to have high biosoluble glass fiber compositions that have a free energy of hydration greater than (more positive than) -5.00 kilocalories (kcal) per mole.